The crosscutting green budget instrument invites to examine the state budget in relation to its international and national environmental commitments. The empirical fieldwork in Costa Rica analyses the multiplicity of ministerial actors and international cooperation actors that are involved in the design of an instrument at the national level. Shaped by international prescriptions, the green budget process in Costa Rica emerged in a specific context of international cooperation in the country. It is also the result of co-design between Costa Rican administrations and international cooperation agents. The design of this instrument takes place in a national context fed by contradictions and environmental threats exacerbated by the economic development model based on agro-exportation. Thus, the objective of this communication is to propose some tracks of analysis to understand how the design of an instrument of public action at the national level between Costa Rican national administrations and international cooperation is working.